Clinical Trials of a Living Dermal Tissue Replacement Placed Beneath Meshed, Split-Thickness Skin Grafts on Excised Burn Wounds

We evaluated the ability of Dermagraft (Advanced Tissue Sciences, La Jolla, Calif.), a living tissue analog that is composed of human neonatal fibroblasts, which are grown on a polyglactin acid Vicryl mesh (Ethicon Inc., Somerville, N.J.), to function as a dermal replacement when placed beneath meshed, expanded split-thickness skin grafts (MESTSGs). Full-thickness burn wounds in 17 patients with burns (mean age, 31 years; range, 6 to 69 years; mean burn size, 23.8% total body surface area) were excised to subcutaneous fat (nine patients), to fascia (three patients), or to a combination of deep dermis and fat (five patients). Dermagraft was placed over the experimental sites, which were then covered with MESTSGs. Paired control sites on each patient received MESTSGs only. The results showed that "take" of MESTSGs on control sites was slightly better than take on experimental sites that contained the Dermagraft; however, the differences were not statistically significant. Mesh interstices epithelialized over the surface of the full-thickness wound (control sites) or over the surface of Dermagraft (experimental sites). Wound biopsy specimens demonstrated no evidence of rejection of the cultured allogeneic fibroblasts and minimal inflammatory reaction to the Vicryl fibers. Evidence of continuous basement membrane formation at the epithelial-Dermagraft junction, which was identified by immunohistochemical staining for laminin and type IV collagen, was seen by day 14 beneath the healed epithelium in the skin graft interstices. The Vicryl fibers were hydrolyzed in the wound over a 2-to-4-week period, although some expulsion of fibers occurred as the healing epithelium advanced to close the MESTSG interstices. Elastic fibers were not seen in neodermal tissue in either control or experimental wounds at periods of up to 1 year after grafting. Further trials with this living tissue replacement are in progress.